As suggested by Ivan Gerasimov.

diff -r dc913ab01067 src/java.base/share/classes/java/lang/String.java
--- a/src/java.base/share/classes/java/lang/String.java Fri Mar 02 09:40:07 2018 -0400
+++ b/src/java.base/share/classes/java/lang/String.java Fri Mar 02 10:11:03 2018 -0400
@@ -3001,9 +3001,8 @@
         final byte[] multiple = new byte[limit];
         System.arraycopy(value, 0, multiple, 0, len);
         int copied = len;
- for (int next = copied << 1; next < limit && 0 < next; next = next << 1) {
+ for (; copied < limit - copied; copied <<= 1) {
             System.arraycopy(multiple, 0, multiple, copied, copied);
- copied = next;
         }
         System.arraycopy(multiple, 0, multiple, copied, limit - copied);
         return new String(multiple, coder);